Blood can be extremely difficult to remove, especially from porous surfaces such as concrete. Dried blood is even more complicated to dissolve, particularly when the stain has been sitting for any length of time. Certain chemical products, as well as a variety of organic cleaners, are on the market today that can remove bloodstains. However, the easiest and safest methods for removing bloodstains are simple tricks that you can do on your own with items you likely already have on hand. The best advice, according to Mrs. Clean, is to remove the blood as quickly as possible.
Clean the stain with a sponge soaked in cool water or flush with a high-pressure garden hose. Use a hard-bristle or wire brush and lightly buff any remaining blood. Rinse any residue off with water and allow the area to dry.
Use a solution of water and dish or laundry detergent to treat the blood. Apply a drop of liquid or powder detergent to the blood stain and scrub with hard wire brush. Rinse the area and dry.
Clean blood stained area with an oxygen bleach. Sprinkle or pour the bleach over the stained concrete to thoroughly cover the area. Allow to sit for five minutes and penetrate the stain. Add a small amount of water and scrub with a wire or hard-bristle brush. Rinse the area and allow it to dry.
Use chlorine bleach to remove blood. First test the bleach on a small spot in a hidden area, since bleaching actually changes lightens the color of the stain and can change the shade of concrete. Apply powered or liquid bleach directly to blood, and allow it to soak in for at least five minutes. Rinse with clean water and allow to dry.